Dysarthria and Positive Myasthenia Serology in a 75-Year-Old Man

A 75-year-old man presented with six-month history of speech difficulty, dysphagia, and fatigue that was more pronounced in the evenings. There was no diplopia or ptosis. He developed progressive dyspnea and lost 10 pounds over six months. Repetitive nerve stimulation of the left spinal accessory nerve revealed 15 percent decremental response. Binding AChR antibody titer was increased to 0.5nml/L. He was diagnosed with MG and was transferred to our hospital for plasmaphoresis. Examination is shown. He also had hyperreflexia and mild proximal weakness in the arms.

Challenge Question:
Mild elevation of AChR antibodies in this case:
1. Excluded the diagnosis ALS
2. Indicated coincidental MG and ALS
3. Was an artefact
4. Along with positive RNS, excluded ALS
5. Is reported in ALS

Find the answer and diagnosis in the next edition of Practical Neurology or online, posted along with the patient video at PracticalNeurology.com.

Case selected from Dr. Shaibani’s Video Atlas of Neuromuscular Diseases, in press, by Oxford University Press. Aziz Shaibani, MD, FACP, FAAN is Director of Nerve & Muscle Center of Texas and Clinical Associate Professor of Medicine at Baylor College of Medicine in Houston, TX. He is also Adjunct Professor of Neurology at Kansas University Medical Center in Kansas City, Kansas.